Abstract: This study investigated the effects of four disturbances (enclosure-fertilization, enclosure-burning, fencing and grazing) on organic soil carbon content and density in Loess Plateau. Results are that organic carbon content and density decreased with increased soil depth and the decreasing amount differed for the four disturbances. Different disturbances made different effects on organic soil carbon content. The organic carbon content of 0~50 cm soil layer in the enclosure-fertilization grassland was the highest (from 24.08 to 34.99 g·kg^-1), followed by enclosure-burning grassland (19.59~32.05 g·kg^-1). In the 0~40 cm soil layer, the organic carbon content of grazing grassland was the lowest (from 19.07 to 25.37 g·kg^-1). The effects of four disturbances on organic carbon density were similar to that on organic carbon content. In the 0~50 cm layer, enclosure-fertilized grassland got the highest organic carbon density (14.51 kg·m^-2), followed by enclosure-burning grassland (13.86 kg·m^-2), fencing grassland (12.27 kg·m^-2) and grazing grassland (11.85 kg·m^-2). These findings indicated that human interference could cause significant influence on organic soil carbon content and density of typical grasslands. Grazing could decrease organic soil carbon density while fertilization and fencing could increase it.

Key words: Loess plateau, Typical grassland, Disturbances type, Soil organic carbon content, Organic carbon density

摘要： 以黄土高原典型草原为对象,研究了封育+施肥、封育+火烧、封育和放牧4种干扰类型对土壤有机碳含量和有机碳密度的影响。结果表明:黄土高原典型草原不同干扰类型下土壤有机碳含量和有机碳密度都随土层深度的增加而减少,且干扰类型不同其减少程度不同;不同干扰类型对土壤有机碳含量影响不同。封育+施肥地在0~50 cm各土层有机碳含量均显著高于其他3个干扰类型,变化范围为24.08~34.99 g·kg^-1;其次为封育+火烧地,变化范围为19.59~32.05 g·kg^-1;在0~40 cm各土层,放牧地有机碳含量均最低,为19.07~25.37 g·kg^-1。不同干扰类型对有机碳密度的影响与对有机碳含量的影响基本相似。不同干扰对土壤有机碳的影响主要表现在0~20 cm土壤表层;在0~50 cm土层,4种干扰类型土壤有机碳密度大小依次为:封育+施肥>封育+火烧>封育>放牧,分别为14.51, 13.86, 12.27和11.85 kg·m^-2。综上所述,人为干扰对典型草原土壤有机碳含量和有机碳密度具有明显影响;放牧导致土壤碳密度显著下降,而施肥和封育可以提高土壤碳密度。

关键词: 黄土高原, 典型草原, 干扰类型, 土壤有机碳含量, 有机碳密度